[Molecular epidemiology of norovirus in outbreaks of gastroenteritis in Zhejiang from 2006 to 2007].

Objective: To study the molecular epidemiological characteristics of Norovirus gastroenteritis outbreaks in Zhejiang.

Methods: During January 2006 and December 2007, fecal specimens of patients collected from outbreaks of acute viral gastroenteritis were tested for Norovirus. Epidemiological data were also collected. Noroviruses were detected by a reverse transcription polymerase chain reaction (RT-PCR) and Real-time RT-PCR. Some positive samples were randomly selected and RT-PCR products were sequenced. Comparing to the nucleotide sequences of norovirus genotype I, II reference strains from GenBank, sequence analysis was undertaken based on partial sequence of RNA dependent RNA polymerase (RdRp) and capsid protein (VP1) gene.

Results: 5 outbreaks of viral gastroenteritis caused by Norovirus were reported. A total of 63 stools were obtained from cases with acute gastroenteritis. Noroviruses alone were detected in 45 cases and the illness appeared in autumn. Phylogenetic analysis revealed that Norovirus belonged to G II/G II 4 type. The strains isolated from Zhejiang were almost identical on G II/4 variants that causing epidemics in Beijing and in The Netherlands with the homology of 99.7% and 98.5%-99.0% respectively. Phylogenetic analysis revealed that the isolates were located at the same branch as the norovirus G II/4 variants found in Beijing and Netherlands.

Conclusion: Norovirus is a major cause of outbreaks of viral gastroenteritis in Zhejiang province Genogroup II/4 variants viruses were the prevalent strains.